Boats normally include drain holes located below the waterline, and usually in the lowest part of the hull, to permit drainage of bilge water when the boat is removed from the water for transport or storage. When such a boat plug is not properly installed, water can fill and sink the boat by entering the bottom of the boat through the drain hole.
It is at least embarrassing, and potentially quite costly to launch a boat without such a boat plug being properly installed. It is quite likely that a boat plug can be misplaced, or be stored in a boat in a location not within quick or easy reach of the drain hole. In order to prevent this occurrence some boat plugs have been fastened to the interior of the boat at a location near the drain hole, but this has not always acted as a reminder to install the boat plug before launching the boat nor to remove the boat plug to permit drainage of the boat upon its removal from the water. Additionally, even though a boat plug is readily available near the drain hole, the inward pressure of water resulting from the location of the drain hole at some distance below the surface of the water in which a boat is floating hampers installation of a boat plug.
While there is little risk of a boat sinking upon launching if the plug has been left in the drainhole when the boat is out of water, the boat plug should be removed when the boat is out of water to prevent damage to the interior of the boat. For example, a boat, if left uncovered and unattended, can fill with rain to a level which might damage electrical equipment, promote mildew and rot in the boat or its contents, or result in structural damage should the water freeze.
In order to prevent the risk of sinking a boat upon launching and to prevent damage to a boat or its contents when the boat is out of the water, it is desirable to provide a device for reminding a boat owner to install or remove the boat plug from the boat drain hole at the appropriate times.